Melo M.,University of Edinburgh |
Melo M.,University of Cape Town |
Warren B.H.,UMR C53 PVBMT |
Jones P.J.,University of Edinburgh
Molecular Ecology | Year: 2011
Archipelago-endemic bird radiations are familiar to evolutionary biologists as key illustrations of evolutionary patterns. However, such radiations are in fact rare events. White-eyes (Zosteropidae) are birds with an exceptionally high colonization and speciation potential; they have colonized more islands globally than any other passerine group and include the most species-rich bird genus. The multiplication of white-eye island endemics has been consistently attributed to independent colonizations from the mainland; the white-eyes of the Gulf of Guinea archipelago had been seen as a classic case, spanning as great a breadth of phenotypic diversity as the family worldwide. Contrary to this hypothesis, our molecular phylogenetic analysis places the Gulf of Guinea white-eyes in just two radiations, one grouping all five oceanic island taxa and the other grouping continental island and land-bridge taxa. Numerous 'aberrant' phenotypes (traditionally grouped in the genus Speirops) have evolved independently over a short space of time from nonaberrant (Zosterops) phenotypes; the most phenotypically divergent species have separated as recently as 0.22 Ma. These radiations rival those of Darwin's finches and the Hawaiian honeycreepers in terms of the extent of adaptive radiation per unit time, both in terms of species numbers and in terms of phenotypic diversity. Tempo and patterns of morphological divergence are strongly supportive of an adaptive radiation in the oceanic islands driven by ecological interactions between sympatric white-eyes. Here, very rapid phenotypic evolution mainly affected taxa derived from the youngest wave of colonization, in accordance with the model of asymmetric divergence owing to resource competition in sympatry. © 2011 Blackwell Publishing Ltd.
Dafreville S.,UMR C53 PVBMT |
Payet G.,UMR C53 PVBMT |
Simiand C.,UMR C53 PVBMT |
Risterucci A.M.,CIRAD - Agricultural Research for Development |
And 5 more authors.
Conservation Genetics Resources | Year: 2011
Sideroxylon majus (Sapotaceae) is an endangered endemic tree of La Réunion Island that has suffered from human actions. It is present in small and isolated populations that encounter severe difficulties to regenerate. To have powerful tools for population genetic studies, we have isolated and characterized 14 polymorphic microsatellite markers from S. majus. The 14 loci were tested on 57 individuals from 6 populations. The number of alleles per locus varied from 2 to 20, with an average of 11.8. The observed and expected heterozygosity levels ranged from 0.053 to 1.000, and 0.116 to 0.917, respectively. Six of the 14 loci deviated from Hardy-Weinberg equilibrium. These polymorphic microsatellite markers constitute new tools to study the genetic diversity and spatial genetic structure of S. majus. The cross-species amplifications indicate that most of these loci can be used to investigate population genetic structure in S. grandiflorum, S. boutonianum and S. sessiliflorum. These studies will provide useful results for the elaboration of effective conservation strategies. © Springer Science+Business Media B.V. 2011.